gistfile1.txt

#!/usr/bin/env python

d = {
    'jets': {
        'bad': True
    },
}

e = {'paul': 'loves V'}

def isNested(d):
    for k,v in d.items():
        if type(v).__name__ == 'dict':
            return True
        
    return False
        
        
print isNested(d)
print isNested(e)



$ ./test.py 
True
False